arXiv subjects

Jun He

Publications and source records attributed to Jun He.

At least 271 records · Page 15Linked to original sources

arXiv2017

Interpretation of $Y(4390)$ as an isoscalar partner of $Z(4430)$ from $D^*(2010)\bar{D}_1(2420)$ interaction

Invoked by the recent observation of $Y(4390)$ at BESIII, which is about 40 MeV below the $D^*(2010)\bar{D}_1(2420)$ threshold, we investigate possible bound and resonance states from the $D^*(2010)\bar{D}_1(2420)$ interaction with the one-boson-exchange model in a quasipotential Bethe-Salpeter equation approach. A bound state with quantum number $0^-(1^{--})$ is produced at 4384 MeV from the $D^ (2010)\bar{D}_1(2420)$ interaction, which can be related to experimentally observed $Y(4390)$. Another state with quantum number $1^+(1^{+})$ is also produced at $4461+i39$ MeV from this interaction. Different from the $0^-(1^{--})$ state, the $1^+(1^{+})$ state is a resonance state above the $D^*(2010)\bar{D}_1(2420)$ threshold. This resonance state can be related to the first observed charged charmonium-like state $Z(4430)$, which has a mass about 4475 MeV measured above the threshold as observed at Belle and LHCb. Our result suggests that $Y(4390)$ is an isoscalar partner of the $Z(4430)$ as a hadronic-molecular state from the $D^*(2010)\bar{D}_1(2420)$ interaction.

hep-ph↗

arXiv2017

Derivations, local and 2-local derivations on some algebras of operators on Hilbert C*-modules

For a commutative C*-algebra $\mathcal A$ with unit $e$ and a Hilbert~$\mathcal A$-module $\mathcal M$, denote by End$_{\mathcal A}(\mathcal M)$ the algebra of all bounded $\mathcal A$-linear mappings on $\mathcal M$, and by End$^*_{\mathcal A}(\mathcal M)$ the algebra of all adjointable mappings on $\mathcal M$. We prove that if $\mathcal M$ is full, then each derivation on End$_{\mathcal A}(\mathcal M)$ is $\mathcal A$-linear, continuous, and inner, and each 2-local derivation on End$_{\mathcal A}(\mathcal M)$ or End$^{*}_{\mathcal A}(\mathcal M)$ is a derivation. If there exist $x_0$ in $\mathcal M$ and $f_0$ in $\mathcal M^{'}$, such that $f_0(x_0)=e$, where $\mathcal M^{'}$ denotes the set of all bounded $\mathcal A$-linear mappings from $\mathcal M$ to $\mathcal A$, then each $\mathcal A$-linear local derivation on End$_{\mathcal A}(\mathcal M)$ is a derivation.

math.OA↗

arXiv2017

Generation of polarization squeezed light with an optical parametric amplifier at 795 nm

We report the experimental demonstration of polarization squeezed beam at 795 nm by combining a quadrature squeezed beam with a coherent beam. The quadrature squeezed beam is generated by a degenerate optical parametric amplifier based on a PPKTP crystal. Stokes parameter squeezing of -3.8 dB and anti squeezing of +5.0 dB is observed. This polarization squeezed beam resonant to rubidium D1 line has potential applications in quantum information networks and precise measurement beyond the shot noise limit.

quant-ph↗

arXiv2017

Polarization squeezing at the audio frequency band for the Rubidium D1 line

A 2.8-dB polarization squeezing of the Stokes operator S2 for the rubidium D1 line (795 nm) is achieved, with the lowest squeezing band at an audio frequency of 2.6 kHz. Two methods are applied for improving the squeezing towards low frequencies: an orthogonal-polarized locking beam that precludes residual unwanted interference and quantum noise locking method that stabilizes the relative phase between the squeezed vacuum and the local oscillator. The squeezing level is limited by absorption-induced losses at short wavelengths, here is 397.5 nm. The generated polarization squeezed light can be used in a quantum enhanced magnetometer to increase the measurement sensitivity.

quant-ph↗

arXiv2017

Velocity-selective spectroscopy measurements of Rydberg fine structure states in a hot vapor cell

A velocity-selective spectroscopy technique for studying the spectra from hot Rydberg gases is presented. This method provides high-resolution measurement of the spectrum interval. Based on this method, the velocity-selective hyperfine splitting of intermediate states is measured, as well as the Doppler-free fine-structure splitting of the Rydberg states via two-photon Rydberg excitation in a room-temperature 133Cs vapor cell. The experiment data and theoretical predictions show excellent agreement.

quant-ph↗

arXiv2017

Commissioning of te China-ADS injector-I testing facility

The 10 MeV accelerator-driven subcritical system (ADS) Injector-I test stand at Institute of High Energy Physics (IHEP) is a testing facility dedicated to demonstrate one of the two injector design schemes [Injector Scheme-I, which works at 325 MHz], for the ADS project in China. The Injector adopted a four vane copper structure RFQ with output energy of 3.2 MeV and a superconducting (SC) section accommodating fourteen \b{eta}g=0.12 single spoke cavities, fourteen SC solenoids and fourteen cold BPMs. The ion source was installed since April of 2014, periods of commissioning are regularly scheduled between installation phases of the rest of the injector. Continuous wave (CW) beam was shooting through the injector and 10 MeV CW proton beam with average beam current around 2 mA was obtained recently. This contribution describe the results achieved so far and the difficulties encountered in CW commissioning.

physics.acc-ph↗

arXiv2017

Analysis of recent CLAS data on $f_{1}(1285)$ photoproduction

Based on the experimental data released recently by the CLAS Collaboration, the $f_{1}(1285)$ photoproduction off a proton target is investigated in an effective Lagrangian approach. In our model, $s$-channel, $u$-channel, and $t$-channel Born terms are included to calculate the differential cross sections, which are compared with the recent CLAS experiment. An interpolating Reggeized treatment is applied to the $t$ channel, and it is found that the $t$-channel contribution is dominant in the $f_1(1285)$ photoproduction and the $u$-channel contribution is responsible for the enhancement at backward angles. The present calculation does not take into account any explicit $s$-channel nucleon-resonance contribution; nevertheless, our model provides a good description of the main features of the data. It suggests small couplings of the $f_1(1285)$ and the nucleon resonances in this energy region.

nucl-th↗

arXiv2017

Nucleon resonances $N(1875)$ and $N(2100)$ as strange partners of LHCb pentaquarks

In this work, we investigate the possibility of interpreting two nucleon resonances, the $N(1875)$ and the $N(2100)$, as hadronic molecular states from the $Σ^*K$ and $ΣK^*$ interactions, respectively. With the help of effective Lagrangians in which coupling constants are determined by the SU(3) symmetry, the $Σ^*K$ and $ΣK^*$ interactions are described by the vector-meson and pseudoscalar-meson exchanges. With the one-boson-exchange potential obtained, bound states from the $Σ^*K$ and $ΣK^*$ interactions are searched for in a quasipotential Bethe-Saltpeter equation approach. A bound state with quantum number $I(J^P)=1/2(3/2^-)$ is produced from the $Σ^*K$ interaction, which can be identified as the $N(1875)$ listed in PDG. It can be seen as a strange partner of the LHCb pentaquark $P_c(4380)$ with the same quantum numbers in the molecular state picture. The $ΣK^*$ interaction also produces a bound state with quantum number $I(J^P)=1/2(3/2^-)$, which is related to experimentally observed $N(2100)$ in the $ϕ$ photoproduction. Our results suggest that the $N(2120)$ observed in the $KΛ(1520)$ photoproduction and the $N(2100)$ observed in the $ϕ$ photoproduction have different origins. The former is a conventional three-quark state while the latter is a $ΣK^*$ molecular state, which can be seen as a strange partner of the $P_c(4450)$ with different spin parity.

hep-ph↗

arXiv2017

Understanding spin parity of $P_c(4450)$ and $Y(4274)$ in a hadronic molecular state picture

The hidden-charmed pentaquark $P_c(4450)$ and the charmonium-like state $Y(4274)$ are investigated as a $\bar{D}^*Σ_c$ and a $D_s\bar{D}_{s0}(2317)$ molecular state, respectively. The spin parities of these two states cannot be well understood if only S-wave $\bar{D}^*Σ_c$ and $D_s\bar{D}_{s0}(2317)$ interactions are considered. In this work, the interactions are studied in a quasipotential Bethe-Salpeter equation approach with a partial wave decomposition on spin parity $J^P$, and the contributions of different partial waves are studied in a two-channel scattering model including a generating channel and an observation channel. Two poles at $4447\pm4i$ and $4392\pm46i$ MeV are produced from the $\bar{D}^*Σ_c$ interaction coupled with the $J/ψp$ channel in $3/2^-$ wave and $5/2^+$ wave, respectively. The peak for the $5/2^+$ state has a comparable height as that of the $3/2^-$ state in the $J/ψp$ invariant mass spectrum. The $D_s\bar{D}_{s0}(2317)$ interaction coupled with the $J/ψϕ$ channel is studied and a pole at $4275\pm11i$ MeV is produced in $J^{P}=1^{+}$ wave, which corresponds to P-wave $D_s\bar{D}_{s0}(2317)$ interaction. The pole from S-wave $D_s\bar{D}_{s0}(2317)$ interaction is far below that from P-wave interaction even the $J/ψϕ$ threshold, so cannot be observed in the $J/ψϕ$ channel. The result suggests that in these cases a state carrying a spin parity corresponding to P-wave interaction should be taken as seriously as these carrying a spin parity corresponding to S-wave interaction in the hadronic molecular state picture.

hep-ph↗

arXiv2017

The hidden-charm multiquark states

Since 2003 many charmonium-like states were observed experimentally. Especially those charged charmonium-like $Z_c$ states and bottomonium-like $Z_b$ states cannot be accommodated within the naive quark model, which are good candidates of either the hidden-charm tetraquark states or molecules composed of a pair of charmed mesons. In 2015, the LHCb Collaboration discovered two hidden-charm pentaquark states, which are also beyond the quark model. In this talk, we review the current experimental progress and investigate various theoretical interpretations of these candidates of the multiquark states. We list the puzzles and theoretical challenges of these models when confronted with the experimental data. We also discuss possible future measurements which may distinguish the theoretical schemes on the underlying structures of the hidden-charm multiquark states.

hep-ph↗

arXiv2016

Hadronic molecular states from the $K\bar{K}^*$ interaction

In this work, the $K\bar{K}^*$ interaction is studied in a quasipotential Bethe-Salpeter equation approach combined with the one-boson-exchange model. With the help of the hidden-gauge Lagrangian, the exchanges of pseudoscalar mesons ($π$ and $η$) and vector mesons ($ρ$, $ω$ and $ϕ$) are considered to describe the $K\bar{K}^*$ interaction. Besides the direct vector-meson exchange which can be related to the Weinberg-Tomozawa term, pseudoscalar-meson exchanges also play important roles in the mechanism of the $K\bar{K}^*$ interaction. The poles of scattering amplitude are searched to find the molecular states produced from the $K\bar{K}^*$ interaction. In the case of quantum number $I^G(J^{PC})=0^+(1^{++})$, a pole is found with a reasonable cutoff, which can be related to the $f_1(1285)$ in experiment. Another bound state with $0^-(1^{+-})$ is also produced from the $K\bar{K}^*$ interaction, which can be related to the $h_1(1380)$. In the isovector sector, the interaction is much weaker and a bound state with $1^+(1^{+})$ relevant to the $b_1(1235)$ is produced but at a larger cutoff. Our results suggest that in the hadronic molecular state picture the $f_1(1285)$ and $b_1(1235)$ are the strange partners of the $X(3872)$ and $Z_c(3900)$, respectively.

hep-ph↗

arXiv2016

Amplification of nanosecond laser pulse chain via dynamic injection locking of laser diode

We report a novel optical pulse generation method for high-speed wavelength switching of amplified nanosecond (ns) laser pulses resonant to atomic transitions.Under free-running condition, a slave laser diode is blue-detuned with tens of GHz relative to the master laser. A ns pulse chain generated by modulating the continuous-wave master laser with a fiber-pigtailed electro-optical intensity modulator is injected into the slave laser diode to fast switch the slave laser's wavelength back and forth. The output beam of slave laser is filtered by a temperature-controlled etalon to get the amplified pulse chain. Based on our dynamic injection locking scheme, we produce a ns-scale square pulse chain with an effective ON/OFF ratio 10^8, considering at least the 60 dB scattering suppression by tuning light-atom interactions with far off-resonance detuning and 26.7 dB suppression ratio of the etalon. By studying the dynamic processes of injection locking, we determine the dependence of injection locking on both the injection power and the frequency detuning.

physics.optics↗

arXiv2016

An Analytic Expression of Relative Approximation Error for a Class of Evolutionary Algorithms

An important question in evolutionary computation is how good solutions evolutionary algorithms can produce. This paper aims to provide an analytic analysis of solution quality in terms of the relative approximation error, which is defined by the error between 1 and the approximation ratio of the solution found by an evolutionary algorithm. Since evolutionary algorithms are iterative methods, the relative approximation error is a function of generations. With the help of matrix analysis, it is possible to obtain an exact expression of such a function. In this paper, an analytic expression for calculating the relative approximation error is presented for a class of evolutionary algorithms, that is, (1+1) strictly elitist evolution algorithms. Furthermore, analytic expressions of the fitness value and the average convergence rate in each generation are also derived for this class of evolutionary algorithms. The approach is promising, and it can be extended to non-elitist or population-based algorithms too.

cs.NE↗

arXiv2016

$\bar{D}Σ^_c$ and $\bar{D}^Σ_c$ interactions and LHCb pentaquarks

Recently, LHCb collaboration reported the observation of two hidden-charmed resonances $P_c(4380)$ and $P_c(4450)$ consistent with hidden-charmed pentaquarks. We perform a dynamical investigation about the $\bar{D}Σ_c^*(2520)$ and $\bar{D}^*Σ_c(2455)$ interactions which are described by the meson exchanges in a quasipotential Bethe-Salpeter equation approach. Two poles around $4450$ and $4390$ MeV are produced from the $\bar{D}^*Σ_c(2455)$ interaction with spin parities $3/2^-$ and $5/2^+$, respectively. The peak for $5/2^+$ state has a comparable hight as that of $3/2^-$ state in the $J/ψp$ invariant mass spectrum. Another bound state with spin-parity $J^P=3/2^-$ is produced from the $\bar{D}Σ^*_c(2520)$ interaction. Such results suggest that the narrower LHCb pentaquark $P_c(4450)$ can be well interpreted as a $5/2^+$ $\bar{D}^*Σ_c(2455)$ molecular state while the $P_c(4380)$ is a $3/2^-$ $\bar{D}^*Σ_c(2455)$ molecular state mixed with other secondary origins.

hep-ph↗

arXiv2016

Characterizations of Jordan mappings on some rings and algebras through zero products

Let $\mathcal{U}=\left[ \begin{array}{cc} \mathcal{A} & \mathcal{M} \mathcal{N}& \mathcal{B} \end{array} \right]$ be a generalized matrix ring, where $\mathcal{A}$ and $\mathcal{B}$ are 2-torsion free. We prove that if $ϕ:\mathcal{U}\rightarrow \mathcal{U}$ is an additive mapping such that $ϕ(U)\circ V+U\circ ϕ(V)=0$ whenever $UV=VU=0,$ then $ϕ=δ+η$, where $δ$ is a Jordan derivation and $η$ is a multiplier. As its applications, we prove that the similar conclusion remains valid on full matrix algebras, unital prime rings with a nontrivial idempotent, unital standard operator algebras, CDCSL algebras and von Neumann algebras.

math.OA↗

arXiv2016

Photodetecting and Light-Emitting Devices Based on Two Dimensional Materials

Two dimensional (2D) materials, e.g. graphene, transition metal dichalcogenides (TMDs), black phosphorus (BP), have demonstrated fascinating electrical and optical characteristics and exhibited great potential in optoelectronic applications. High performance and multifunctional devices were achieved by employing diverse designs of architectures, such as hybrid systems with nanostructured materials, bulk semiconductors and organics, forming 2D heterostructures. In this review, we mainly discuss the recent progresses of 2D materials in high responsive photodetectors, light-emitting devices and single photon emitters. Hybrid systems and van der Waals heterostructures based devices are emphasized, which exhibit great potential in state-of-the-art applications.

cond-mat.mtrl-sci↗

arXiv2016

Characterizations of 2-local derivations and local Lie derivations on some algebras

We prove that every 2-local derivation from the algebra $M_n(\mathcal{A})(n>2)$ into its bimodule $M_n(\mathcal{M})$ is a derivation, where $\mathcal{A}$ is a unital Banach algebra and $\mathcal{M}$ is a unital $\mathcal{A}$-bimodule such that each Jordan derivation from $\mathcal{A}$ into $\mathcal{M}$ is an inner derivation, and that every 2-local derivation on a C*-algebra with a faithful traceable representation is a derivation. We also characterize local and 2-local Lie derivations on some algebras such as von Neumann algebras, nest algebras, Jiang-Su algebra and UHF algebras.

math.OA↗

arXiv2016

Characterizations of centralizers and derivations on some algebras

A linear mapping $ϕ$ on an algebra $\mathcal{A}$ is called a centralizable mapping at $G\in\mathcal{A}$ if $ϕ(AB)=ϕ(A)B=Aϕ(B)$ for each $A$ and $B$ in $\mathcal{A}$ with $AB=G$, and $ϕ$ is called a derivable mapping at $G\in\mathcal{A}$ if $ϕ(AB)=ϕ(A)B+Aϕ(B)$ for each $A$ and $B$ in $\mathcal{A}$ with $AB=G$. A point $G$ in $\mathcal{A}$ is called a full-centralizable point (resp. full-derivable point) if every centralizable (resp. derivable) mapping at $G$ is a centralizer (resp. derivation). We prove that every point in a von Neumann algebra or a triangular algebra is a full-centralizable point. We also prove that a point in a von Neumann algebra is a full-derivable point if and only if its central carrier is the unit.

math.OA↗